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Natassia Rodrigo and Samantha Hocking

Summary

This case illustrates the exceedingly rare phenomenon of transient diabetes insipidus, in association with pre-eclampsia, occurring in the post-partum period following an in vitro fertilisation pregnancy, in an otherwise well 48-year-old lady. Diabetes insipidus can manifest during pregnancy, induced by increased vasopressinase activity secreted by placental trophoblasts and usually manifests in the third trimester. This presentation elucidates not only the intricate balance between the physiology of pregnancy and hormonal homeostasis, but also the importance of post-partum care as the physiological changes of pregnancy still hold pathological potential in the weeks immediately following delivery.

Learning points:

Diabetes insipidus (DI) is a rare complication of pregnancy occurring in 1 in 30 000 pregnancies.

It is associated with excessive vasopressinase activity, secreted by placental trophoblasts, which increases the rate of degradation of anti-diuretic hormone.

It is responsive to synthetic desmopressin 1-deanimo-8-d-arginine vasopressin as this form is not degraded by placental vasopressinase.

Vasopressinase is proportional to placental weight, which is increased in pregnancies conceived with assisted reproductive techniques including in vitro fertilisation.

Summary

A 28-year-old male presented with 2 days of vomiting and abdominal pain, preceded by 2 weeks of thirst, polyuria and polydipsia. He had recently started risperidone for obsessive-compulsive disorder. He reported a high dietary sugar intake and had a strong family history of type 2 diabetes mellitus (T2DM). On admission, he was tachycardic, tachypnoeic and drowsy with a Glasgow Coma Scale (GCS) of 10/15. We noted axillary acanthosis nigricans and obesity (BMI 33.2 kg/m2). Dipstick urinalysis showed ketonuria and glycosuria. Blood results were consistent with diabetic ketoacidosis (DKA), with hyperosmolar state. We initiated our DKA protocol, with intravenous insulin, fluids and potassium, and we discontinued risperidone. His obesity, family history of T2DM, acanthosis nigricans and hyperosmolar state prompted consideration of T2DM presenting with ‘ketosis-prone diabetes’ (KPD) rather than T1DM. Antibody markers of beta-cell autoimmunity were subsequently negative. Four weeks later, he had modified his diet and lost weight, and his metabolic parameters had normalised. We reduced his total daily insulin dose from 35 to 18 units and introduced metformin. We stopped insulin completely by week 7. At 6 months, his glucometer readings and glycated haemoglobin (HbA1c) level had normalised.

Learning points:

Risperidone-induced diabetic ketoacidosis (DKA) is not synonymous with type 1 diabetes, even in young white patients and may be a manifestation of ‘ketosis-prone’ type 2 diabetes (KPD).

KPD is often only confirmed after the initial presentation, when islet autoimmunity and cautious phasing out of insulin therapy have been assessed, and emergency DKA management remains the same.

As in other cases of KPD, a family history of T2DM and presence of cutaneous markers of insulin resistance were important clinical features suggestive of an alternative aetiology for DKA.

Senhong Lee, Aparna Morgan, Sonali Shah and Peter R Ebeling

Summary

We report a case of a 67-year-old man with type 2 diabetes presented with diabetic ketoacidosis, two weeks after his first dose of nivolumab therapy for non–small-cell lung carcinoma. He was started on empagliflozin two days prior in the setting of hyperglycaemia after the initiation of nivolumab therapy. Laboratory evaluation revealed an undetectable C-peptide and a positive anti-glutamic acid decarboxylase (GAD) antibody. He was treated with intravenous fluids and insulin infusion and was subsequently transitioned to subcutaneous insulin and discharged home. He subsequently has developed likely autoimmune thyroiditis and autoimmune encephalitis.

Snezana Burmazovic, Christoph Henzen, Lukas Brander and Luca Cioccari

Summary

The combination of hyperosmolar hyperglycaemic state and central diabetes insipidus is unusual and poses unique diagnostic and therapeutic challenges for clinicians. In a patient with diabetes mellitus presenting with polyuria and polydipsia, poor glycaemic control is usually the first aetiology that is considered, and achieving glycaemic control remains the first course of action. However, severe hypernatraemia, hyperglycaemia and discordance between urine-specific gravity and urine osmolality suggest concurrent symptomatic diabetes insipidus. We report a rare case of concurrent manifestation of hyperosmolar hyperglycaemic state and central diabetes insipidus in a patient with a history of craniopharyngioma.

Learning points:

In patients with diabetes mellitus presenting with polyuria and polydipsia, poor glycaemic control is usually the first aetiology to be considered.

However, a history of craniopharyngioma, severe hypernatraemia, hyperglycaemia and discordance between urine-specific gravity and osmolality provide evidence of concurrent diabetes insipidus.

Therefore, if a patient with diabetes mellitus presents with severe hypernatraemia, hyperglycaemia, a low or low normal urinary-specific gravity and worsening polyuria despite correction of hyperglycaemia, concurrent diabetes insipidus should be sought.

Ali A Zaied, Halis K Akturk, Richard W Joseph and Augustine S Lee

Summary

Nivolumab, a monoclonal antibody against programmed cell death-1 receptor, is increasingly used in advanced cancers. While nivolumab use enhances cancer therapy, it is associated with increased immune-related adverse events. We describe an elderly man who presented in ketoacidosis after receiving nivolumab for metastatic renal cell carcinoma. On presentation, he was hyperpneic and laboratory analyses showed hyperglycemia and anion-gapped metabolic acidosis consistent with diabetic ketoacidosis. No other precipitating factors, besides nivolumab, were identified. Pre-nivolumab blood glucose levels were normal. The patient responded to treatment with intravenous fluids, insulin and electrolyte replacement. He was diagnosed with insulin-dependent autoimmune diabetes mellitus secondary to nivolumab. Although nivolumab was stopped, he continued to require multiple insulin injection therapy till his last follow-up 7 months after presentation. Clinicians need to be alerted to the development of diabetes mellitus and diabetic ketoacidosis in patients receiving nivolumab.

Learning points:

Diabetic ketoacidosis should be considered in the differential of patients presenting with metabolic acidosis following treatment with antibodies to programmed cell death-1 receptor (anti-PD-1).

Autoimmune islet cell damage is the presumed mechanism for how insulin requiring diabetes mellitus can develop de novo following administration of anti-PD-1.

Because anti-PD-1 works by the activation of T-cells and reduction of ‘self-tolerance’, other autoimmune disorders are likely to be increasingly recognized with increased use of these agents.

Summary

Five days following the 3rd cycle of nivolumab, a monoclonal antibody, which acts as immune checkpoint inhibitor against the programmed cell death protein-1, for metastatic lung adenocarcinoma, a 56-year-old woman presented at the hospital critically ill. On admission, she had severe diabetic ketoacidosis (DKA), as evidenced by venous glucose of 47 mmol/L, blood ketones of 7.5 mmol/L, pH of 6.95 and bicarbonate of 6.6 mmol/L. She has had no personal or family history of diabetes mellitus (DM), while random venous glucose, measured 1 week prior to hospitalisation, was 6.1 mmol/L. On admission, her HbA1c was 8.2% and anti-GAD antibodies were 12 kIU/L (0–5 kU/L), while islet cell antibodies and serum C-peptide were undetectable. Nivolumab was recommenced without the development of other immune-mediated phenomena until 6 months later, when she developed hypothyroidism with TSH 18 U/L and low free T4. She remains insulin dependent and has required levothyroxine replacement, while she has maintained good radiological and clinical response to immunotherapy. This case is notable for the rapidity of onset and profound nature of DKA at presentation, which occurred two months following commencement of immunotherapy. Despite the association of nivolumab with immune-mediated endocrinopathies, only a very small number of patients developing type 1 DM has been reported to date. Patients should be closely monitored for hyperglycaemia and thyroid dysfunction prior to and periodically during immunotherapy.

Florence Gunawan, Elizabeth George and Adam Roberts

Summary

Immune checkpoint inhibitors are the mainstay of treatment for advanced melanoma, and their use is being increasingly implicated in the development of autoimmune endocrinopathies. We present a case of a 52-year-old man with metastatic melanoma on combination nivolumab and ipilumimab therapy who developed concurrent hypophysitis, type 1 diabetes mellitus (T1DM) and diabetes insipidus. He presented prior to third cycle of combination treatment with a headache, myalgias and fatigue. Biochemistry and MRI pituitary confirmed anterior pituitary dysfunction with a TSH: 0.02 mU/L (0.5–5.5 mU/L), fT4: 5.2 pmol/L (11–22 pmol/L), fT3: 4.0 pmol/L (3.2–6.4 pmol/L), cortisol (12:00 h): <9 nmol/L (74–286 nmol/L), FSH: 0.7 IU/L (1.5–9.7 IU/L), LH: <0.1 IU/L (1.8–9.2 IU/L), PRL: 1 mIU/L (90–400 mIU/L), SHBG: 34 nmol/L (19–764 nmol/L) and total testosterone: <0.4 nmol/L (9.9–27.8 nmol/L). High-dose dexamethasone (8 mg) was administered followed by hydrocortisone, thyroxine and topical testosterone replacement. Two weeks post administration of the third cycle, he became unwell with lethargy, weight loss and nocturia. Central diabetes insipidus was diagnosed on the basis of symptoms and sodium of 149 mmol/L (135–145 mmol/L). Desmopressin nasal spray was instituted with symptom resolution and normalization of serum sodium. Three weeks later, he presented again polyuric and polydipsic. His capillary glucose was 20.8 mmol/L (ketones of 2.4 mmol), low C-peptide 0.05 nmol/L (0.4–1.5 nmol/L) and HbA1c of 7.7%. T1DM was suspected, and he was commenced on an insulin infusion with rapid symptom resolution. Insulin antibodies glutamic acid decarboxylase (GAD), insulin antibody-2 (IA-2) and zinc transporter-8 (ZnT8) were negative. A follow-up MRI pituitary revealed findings consistent with recovering autoimmune hypophysitis. Immunotherapy was discontinued based on the extent of these autoimmune endocrinopathies.

Learning points:

The most effective regime for treatment of metastatic melanoma is combination immunotherapy with nivolumab and ipilumimab, and this therapy is associated with a high incidence of autoimmune endocrinopathies.

Given the high prevalence of immune-related adverse events, the threshold for functional testing should be low.

Traditional antibody testing may not be reliable to identify early-onset endocrinopathy.

Routine screening pathways have yet to be adequately validated through clinical trials.

Summary

A variety of neoplastic, inflammatory and congenital conditions can cause pituitary stalk thickening. Differentiating between these causes is important as targeted treatment may be offered. Diagnostic work-up consists of a thorough history, examination, biochemical analysis and imaging. We present the case of a 33-year-old male who presented with diabetes insipidus and had pituitary stalk thickening on magnetic resonance imaging. Further investigations revealed an elevated CSF βhCG, which raised the possibility of an intracranial germ cell tumor. However, when repeated on four different assays, the βhCG levels were discordant. On serial imaging, the pituitary stalk thickening reduced slightly, which would be unexpected for a germ cell tumor. This case raises the difficulties interpreting CSF βhCG, as not all immunoassays for βhCG have been validated for use in CSF. The Roche Diagnostics Elecsys and Siemens Centaur assays have been validated for CSF βhCG, and so we advocate using one of these methods. If unavailable or serum/CSF results are ambiguous, serial MRI is appropriate, with pituitary stalk biopsy considered if the stalk measures >6.5 mm or other imaging abnormalities are present.

Learning points:

Most adult patients with central diabetes insipidus have imaging abnormalities on a pituitary MRI. The most common abnormalities are loss of the posterior pituitary bright spot and pituitary stalk thickening, both of which are non-specific.

Investigation of pituitary stalk thickening should encompass the many possible causes and include biochemical analyses as well as imaging of the chest, abdomen and pelvis. Further investigations should be guided by the clinical context, but may include testicular ultrasound, CSF analysis and pituitary stalk biopsy.

Germ cell tumors involving the pituitary stalk may be suspected on clinical grounds, but in the absence of a tissue diagnosis (biopsy) confirmation may be difficult and relies on biochemical assessment of blood and possibly CSF as well as serial MRI imaging.

CSF βhCG levels should be analyzed on an instrument validated for use in CSF or on multiple instruments, and the pitfalls of testing this marker (false negative in some germ cell tumors, false positives in other conditions, lack of internationally agreed reference ranges for diagnosing germ cell tumors) should be considered when interpreting the results.

Summary

A 26-year-old woman presented with severe postpartum headaches. Magnetic resonance imaging (MRI) revealed a symmetric, heterogeneous enlargement of the pituitary gland. Three months later, she developed central diabetes insipidus. A diagnosis of postpartum hypophysitis was suspected and corticosteroids were prescribed. Six months later, the pituitary mass showed further enlargement and characteristics of a necrotic abscess with a peripheral shell and infiltration of the hypothalamus. Transsphenoidal surgery was performed, disclosing a pus-filled cavity which was drained. No bacterial growth was observed, except a single positive blood culture for Staphylococcus aureus, considered at that time as a potential contaminant. A short antibiotic course was, however, administered together with hormonal substitution for panhypopituitarism. Four months after her discharge, severe headaches recurred. Pituitary MRI was suggestive of a persistent inflammatory mass of the sellar region. She underwent a new transsphenoidal resection of a residual abscess. At that time, the sellar aspiration fluid was positive for Staphylococcus aureus and she was treated with antibiotics for 6 weeks, after which she had complete resolution of her infection. The possibility of a pituitary abscess, although rare, should be kept in mind during evaluation for a necrotic inflammatory pituitary mass with severe headaches and hormonal deficiencies.

Learning points:

The possibility of a pituitary abscess, although rare, should be kept in mind during evaluation for a necrotic inflammatory pituitary mass with severe headaches and hormonal deficiencies.

In a significant proportion of cases no pathogenic organism can be isolated.

A close follow-up is necessary given the risk of recurrence and the high rate of postoperative pituitary deficiencies.

Summary

Lithium-induced nephrogenic diabetes insipidus (Li-NDI) is a rare and difficult-to-treat condition. A study in mice and two recent papers describe the use of acetazolamide in Li-NDI in 7 patients (a case report and a 6 patient series). We describe the case of a 63-year-old woman with bipolar disorder treated with lithium and no previous history of diabetes insipidus. She was hospitalized due to a bowel obstruction and developed severe dehydration after surgery when she was water deprived. After desmopressin administration and unsuccessful thiazide and amiloride treatment, acetazolamide was administrated to control polyuria and hydroelectrolytic disorders without significant side effects. To our knowledge, this is the third publication on acetazolamide use in Li-NDI patients.